Method of forming a double torsion spring and machine therefor

ABSTRACT

A wire forming machine and method wherein a length of wire is cut and provided with a bow-shape at a coiling station by forming jaws moving relative to a forming arbor and with a pair of wire legs lying to either side of a stationary element at the coiling station. Right and left tool slides each carry a rotatable coiling head which is advanced into engagement with the wire legs and with catch pins on the coiling heads engaging and holding the wire whereby rotation of the coiling heads will form coils in each of the wire legs. The central bowed wire base is free to advance toward the coiling heads while being restrained against rotation whereby the lengths of wire to form the coils are provided by the advancing wire base, rather than by shortening of the free ends of the wire legs.

United States Patent Strzepek 1 July 18,1972

[54] METHOD OF FORMING A DOUBLE TORSION SPRING AND MACHINE THEREFOREdward S. Strzepek, Cicero, lll.

Assignee: Lewis Spring & Manufacturing Co.

Filed: June 23, 1970 Appl. No.: 49,075

Inventor:

Field of Search ..140/102, 103, 104, 92; 72/129,72/130,l31,l33,135,137,142

[56] References Cited UNITED STATES PATENTS 237,397 2/1881 Lewthwaite..l40/l03 3,227,195 1/1966 Stegmann 140/103 Primary Examiner-Lowell A.Larson Attorney-Hofgren, Wegner, Allen, Stellman & McCord [57] ABSTRACTA wire forming machine and method wherein a length of wire is cut andprovided with a bow-shape at a coiling station by forming jaws movingrelative to a forming arbor and with a pair of wire legs lying to eitherside of a stationary element at the coiling station. Right and left toolslides each carry a rotatable coiling head which is advanced intoengagement with the wire legs and with catch pins on the coiling headsengaging and holding the wire whereby rotation of the coiling heads willform coils in each of the wire legs. The central bowed wire base is freeto advance toward the coiling heads while being restrained againstrotation whereby the lengths of wire to form the coils are provided bythe advancing wire base, rather than by shortening of the free ends ofthe wire legs.

14 Claims, 8 Drawing Figures fff fjjjflijli- I: IYIQILKKJlllllllllllllllllllllllllllllllllllllllllllllllllli PATENTED JUL] 8 I972SHEET 1 UF 3 PATENTED JUL] 81972 SHEET 2 (IF 3 METHOD OF FORMING ADOUBLE TORSION SPRING AND MACHINE THEREFOR BACKGROUND OF THE INVENTIONThis invention pertains to wire forming machines and tooling therefor toform double torsion springs, along with a new and improved method offorming such springs without the performance of secondary operations inplural machines and with the number of coils formed in the torsionspring not being limited by the free ends of the wire legs, since saidfree ends are not caused to shorten during the coiling operation. Thisresults in not having long lengths of wire rotated during the coilingoperation.

It is known in the prior art to form double torsion springs by firstforming a wire length into a U-shape with a wire base and a pair oflegs, commonly called a staple, and then individually placing thesestaples in a kick press along with a coiling adapter slipped onto thearbor of the kick press, followed by rotation of the arbor to form thecoils and with the wire being pulled around the arbor from the free endsof the wire legs. Another known system utilizing a four-slide machine isto cut off a length of wire and from it into a U-shape, followed bycoiling of the legs, with the lengths of wire for the coils beingprovided by shortening of the free ends of the wire legs during coiling.

In the first of these known systems, two successive operations, indifferent machines, are required, with the mounting and removal of anadapter in forming each spring. In the second known system, utilizing afour-slide machine, there are definite limitations, since the number ofcoils to be made are limited by the amount of wire in the legs which isfree to rotate during the coiling operation without obstruction with thesurrounding parts of the machine. This limits the number of coils to beformed to a length of the free wire legs which will still not beobstructed by the machine as the free ends rotate during the coilingoperation.

SUMMARY OF THE INVENTION An object of this invention is to provide a newand improved method of forming double torsion springs wherein the numberof coils are not limited by the amount of wire in the wire legs that canfreely rotate in the coiling operation, but wherein the number of coilsare theoretically unlimited since the free ends of the wire legs do notchange in length during coiling but the wire for coiling is provided bypermitting the base of the U- shaped wire to advance without rotationduring coiling.

Another object of the invention is to provide a machine and toolingtherefor for forming double torsion springs wherein at a coiling stationa forming arbor in a lower position coacts with forming jaws on a frontslide to form a bow in a length of wire to have the wire U-shaped, witha pair of legs extending from a central wire base, the forming arborbeing movable to an upper position to subsequently permit advance of thewire base during coiling to provide wire for the coils, a pair of rightand left tool slides each carrying a rotatable coiling head with a catchpin which can be advanced into engagement with the wire legs withrotation thereof causing forming of the coils in each of the legs as thewire base advances theretoward, and with a stationary element havinghorizontal surfaces engaging the wire between the base thereof and thecoiling engagement thereof by the catch pins to permit advance of thewire base while preventing rotation thereof.

Still other objects of the invention are to provide a wire formingmachine and tooling as defined in the preceding paragraph wherein theright and left tool slides carry abutments engageable with the jaws onthe front slide for forming a smooth curve at the wire base, the coilingheads are rotated by rack drives operated from the rear slide cam of themachine through racks interconnected by a bridge and with the racksslidable thereon to permit movement of the coiling heads toward and awayfrom each other while maintaining the rack and pinion drive to thecoiling heads, the provision of a coiling arbor on oneof the coilingheadS which advances into a recess in the other coiling head and whichis of a length to provide an arbor for the coils throughout the entirecoiling operation and as the right and left tool slides retract fromeach other during formation of the coils, the utilization of a surfaceon the forming arbor in its raised position which defines a limit ofadvance for the wire base to provide a controlled length for the basesection of the double torsion spring, as well as other new and improvedstructural features of the machine providing for economical, rapidproduction of double torsion springs.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a four-slidemachine having the tooling associated therewith for forming a doubletorsion spring;

FIG. 2 is a fragmentary plan view on an enlarged scale of the basictooling elements added to the four-slide machine and with parts insection;

FIG. 3 is an elevational view, taken generally along the line 3-3 inFIG. 2;

FIG. 4 is a diagrammatic plan view, showing the elements positioned withthe wire formed into a U-shape or staple and with the coiling headsstill in retracted position;

FIG. 5 is a view, similar to FIG. 4, showing the coiling heads inadvanced position in engagement with the wire for coiling;

FIG. 6 is a fragmentary side elevational view of the structure shown inFIG. 5, preparatory to rotation of the coiling heads to form the coilsin the wire legs;

FIG. 7 is a view similar to FIG. 6 showing the forming arbor elevated topermit advance of the wire base during coiling as indicated by therotation of the coiling head; and

FIG. 8 is a perspective view of a double torsion spring made by themethod and machine disclosed herein.

DESCRIPTION OF THE PREFERRED EMBODIMENT The general machine is shown inFIG. 1, which is of a generally conventional type. The basic machineillustrated is of a type sold by The U.S. Baird Corporation and offeredin a series of different sizes, and known as the Baird Four Slide WireForming Machine. This machine has a base, indicated generally at 10,which receives a wire 11 at the lefthand end thereof with the wireadvancing through a wire straightener, indicated generally at 12, andbeing fed by a feed mechanism, indicated generally at 15, whichreciprocates under the operation of a rotatable crank 16 and connectinglinkage I7 and 18. The advanced length of wire 11 is held by holdingstructure, indicated generally at 20, immediately preceding areciprocable cutter, indicated generally at 21. Beyond the cutter 21 isa coiling station, indicated generally at 22, and with the structure atsaid coiling station being more fully shown in the other Figures of thedrawings.

The machine has a front slide, indicated generally at 25, which isoperable reciprocably in a cycle by a cam 26 mounted on a front slidecam shaft 27 rotatably mounted in the base 10 and with a spring 28 beingprovided for returning of the front slide and to insure following of thecam 26. A right tool slide is indicated generally at 30 and is slidablymounted on the base 10 and with the movement thereof being controlled bya cam 31 on a cam shaft 32 rotatably mounted in the base 10. The cam 31coacts with the follower 35 on the slide and a spring 36 causes thefollower to follow the cam and provide for return movement of the righttool slide. A left tool slide is indicated generally at 40 and isslidably mounted on the base 10 with the movement of this slide beingcontrolled by a cam 41 mounted on a cam shaft 42 rotatably mounted inthe base 10. This cam engages a cam follower 43 on the left tool slideand a spring 44 maintains engagement between the cam and cam followerand causes return movement of the left tool slide.

A rear tool slide, indicated generally at 50, is movably mounted on thebase 10 and is operated by a cam 51 mounted on a rear cam shaft 52rotatable in the base 10. A cam fol lower 53 coacts with the cam 51 anda return spring 54 insures following of the cam 51 by the cam followerand return of the rear tool slide 50.

The rear cam shaft 52 has an additional cam 55 mounted thereon whichcoacts with a follower 56 on a crank arm pivotally mounted to a portionof the base with the opposite end of the crank arm being connected to aforming arbor to be described to provide for movement thereof 5 betweenraised and lowered positions. This crank arm is identified at 57 and isconnected to a block 58 which is attached to the upper end of a formingarbor 60. A return spring 61 provides for following of the cam 55 by thefollower 56. The rear slide 50 does not carry a tool, but has a bridgeand associated rack structure for rotating coiling heads, laterdescribed.

With the structure described, the rotation of the cam shafts and thetiming provided by the cams on the cam shafts as well as rotation of thecrank 16 causes feeding of wire to the coiling station and a sequence ofmovement of the various slides in a manner to be described to formdouble torsion springs.

Referring particularly to FIGS. 2, 4, and 6, a length of wire 11 isshown in FIG. 2, in position between the lower part of the forming arbor60 and the tooling on slide 25. This tooling includes a pair of pivotedjaws 70 and 71 mounted on block 72 and urged towards each other by apair of internally mounted springs 73 and 74. As the front slide 25advances toward the forming arbor 60, the jaws 70 and 71 pass to eitherside of the forming arbor 60 to form the wire into a U-shape or staple,as shown in FIG. 4. As soon as the jaws have engaged the wire againstthe forming arbor, the movement of the cutter 21 is timed to cut thelength of wire off the supply to permit the wire to be formed with awire base 75 (FIG. 4) and with a pair of wire legs 76 and 77 which lieagainst a pair of surfaces 78 and 79 on a vertically extending,stationary element 99 positioned to the rear of the forming arbor 60.These surfaces limit and define the U-shape formed by the forming jaws70 and 71. The operation referred to, as shown in FIG. 4, is with theforming arbor 60 in the lowered position, as shown in FIG. 6, wherein afront edge 80 thereof is at the elevation of the jaws 70 and 71 and withthe jaws being advanced to fully seat the forming arbor to the fulldepth of the jaws.

The next sequence of operation has the cam 55 on the rear cam shaft 52raise the forming arbor 60 to the position shown in FIG. 7 wherein theleading edge 80 is raised above the wire base 75 with a leg 81 of theforming arbor still at the elevation of the wire. At the same time, theright tool slide cam 31 and left tool slide cam 41 advance theirrespective slides toward the coiling location. When these slides areretracted, they are in the position shown in FIGS. 1 and 2. The righttool slide 30 has a block 85 adjustably mounted thereon which rotatablymounts a coiling head 86 having a coiling arbor rotatable therewith, aswell as a catch pin 88. The left-hand tool slide 40 adjustably mounts ablock 90 carrying a coiling head 91 and having a catch pin 92. As shownparticularly with respect to coiling head 91, the head is rotatablymounted within the block 90 and has a pinion 93 which coacts with a rack94 extending rearwardly from the left tool slide 40. A similar pinion isassociated with the coiling head 86 and has a rack 95 extendingrearwardly therefrom. The coiling heads 86 and 91 are shown in retractedposition in FIG. 4 and are shown in advanced, operative position in FIG.5. In the advanced position, the coiling arbor 87 advances through apilot hole 98 in the stationary element 99 having the guiding surfaces78 and 79 and into an internal recess 100 in the coiling head 91.

Each of the coiling heads 86 and 91 are yieldably mounted in theirrespective housings and urged toward each other by a spring-urgedhardened steel ball (not shown).

With the coiling heads positioned as shown in FIG. 5 and with the catchpins 88 and 92 being on top of the wire legs, rotation of the coilingheads 86 and 91 in the direction of the arrow 101 of FIG. 7 will causerotation of the wire about the coiling arbor 87 to form coils in each ofthe wire legs 76 and 77. The catch pins 88 and 92 slightly grip or catchupon the wire legs and cause rotation of the wire without relativemovement therebetween. This requires a supply of wire in forming thecoils which is provided by advance of the wire base 75 toward thecoiling occurring about the coiling arbor 87. This advance is permittedby elevation previously of the forming arbor 60 whereby the wire basecan move from the broken line position, shown in FIG. 7, to a finalposition, shown in full line, wherein the wire base engages against thedepending part 81 of the forming arbor. During this advance of the wirebase, it will be advanced out of the forming jaws 70 and 71, which arestill in position and do not retract until the end of a cycle, when allparts retract.

The wire base 75 is permitted to advance to supply the wire for formingthe coils. However, it does not rotate and is prevented from doing so bythe wire legs 76 and 77 sliding along and in engagement with theunderside of horizontal surfaces 105 and 106 provided in the stationaryelement 99. Referring particularly to FIG. 7, it will be seen thatrotation of the coiling arbor 87 and the catch pin 88 will cause theformation of a coil, with movement of the wire base from left to rightand with the wire leg 77, or the part thereof between the base 75, andthe coiling arbor 87 sliding under the surface 105 to prevent rotationof the wire base 75. The desired number of coils results from thedesired number of revolutions of the coiling heads. As shown in FIG. 8,a resulting double torsion spring with the legs 76 and 77 has wire base75 and with a number of coils formed in each leg.

The rotation of the coiling arbors 86 and 91 and their associated catchpins as well as the coiling arbor 87 is derived from reciprocation ofthe racks 94 and 95 which are interconnected for simultaneous movementby a bridge connected to the rear slide 50 by a member 121. The freeends of each of the racks 94 and 95 are slidably connected to the bridge120 whereby they may move along the length of the bridge as shown inFIG. 2 to permit in and out movement of the coiling heads while stillinsuring simultaneous linear movement thereof under actuation of therear cam 51 to cause simultaneous rotation of the coiling heads. Therear cam is shaped to have the catch pins always return to the rotativeposition shown in FIG. 6 prior to beginning of a cycle.

To form a smooth curve in the wire base 75, each of the tool slides 30and 40 carries an adjustable abutment member and 126, respectively,which, upon advance of the tool slides 30 and 40 toward each other,engage the jaws 70 and 71, as shown in FIG. 4 to squeeze the jaws andimpart a smooth curvature to the wire. This advance causes slightyielding of the coiling heads 86 and 91 as permitted by their springloading.

The cams 31 and 41 associated with the right and left tool slides 30 and40 are contoured to permit slight retracting movement of the tool slides30 and 40 to retract the abutment members 125 and 126 a distance equalto the wire thickness before coiling and further retraction of the toolslides 30 and 40 during coiling to provide progressive separatingmovement of the coiling heads 86 and 91 and a space axially of thetorsion spring as the coils are formed.

After the completion of the double torsion spring, as shown in FIG. 8,the front and rear as well as right and left tool slides all retract andthe forming arbor is lowered to position the parts preparatory to feedof wire for formation of the next spring.

As will be seen, a method is provided herein wherein a length of wire isbent into a U-shape with a pair of legs, the legs are gripped androtated and with the central wire base advancing toward the locationswhere the wire legs are gripped to provide wire length for the coils,whereby the free ends of the completed spring are substantially equal inlength to the free ends of said wire legs beyond the location ofgripping thereof.

It will be seen that the number of coils that can be formed in the legs76 and 77 is substantially unlimited, since although the free ends ofthe wire legs 76 and 77 rotate during the coiling, they need not be of alength to provide wire for forming the coils, since this wire comes fromthe wire base end of the spring. Previously, the number of coils waslimited because the wire for the coils came from the free ends and youcould not have long, free ends of wire rotating during the coilingbecause of contact with nearby parts of the machine.

I claim:

l. The method of forming a double torsion spring comprising thefollowing steps, feeding a continuous length of wire to a formingstation, cutting a section of wire from said wire length at said formingstation, forming the wire section at said forming station into anapproximate U-shape with a pair of spaced legs, and coiling a pluralityof coils in each of said legs simultaneously at said forming station byholding and rotating each of said legs and with the base of the wiresection being held against rotation but movable toward the coils toprovide sufficient wire for the coils, the spacing between the locationswhere the two legs are held increasing as the legs are rotated to formoutwardly extending coils.

2. The method as defined in claim 1 wherein said legs are engaged byrotatable members which slightly bite into the wire.

3. The method as defined in claim 1 wherein said wire base is heldagainst rotation by engaging the top of the wire legs between the wirebase and the coiling location to permit sliding movement of the legs asthe coils are formed.

4. A machine for forming double torsion springs comprising, a base, wirefeeding and straightening means thereon, a coiling station having acenter form with a forming arbor and a stationary element, a front slidewith a bow-forming tool movable onto the forming arbor to form a centerbow in a length of wire to bend the wire into a general U-shape with abase and a pair of legs against the stationary element, left and righttool slides each carrying a rotatable coiling head and a catch pinmovable toward each other to engage the spacedapart wire legs, means forsimultaneously rotating said coiling heads and catch pins to form aplurality of coils in each wire leg with progressive separating movementof the coiling heads, means retracting said forming arbor to permitmovement of said wire base toward the coiling heads to provide wire forthe coils, and means engaging said wire to hold said wire base againstrotation while permitting advance thereof.

5, A machine as defined in claim 4 wherein said forming arbor has asurface in the plane of said wire base after said retraction to define alimit of advance for the wire base in the coiling operation.

6. A machine as defined in claim 4 wherein said stationary element has apilot hole, a coiling arbor extending from one coiling head and of alength to extend through the pilot hole and into a central recess in theopposite coiling head and remain in said recess during said progressiveseparating movement.

7. A machine as defined in claim 4 wherein said bow-forming tool has apair of spaced-apart jaws spring-urged toward each other which movealong opposite sides of said forming arbor to form the center bow, andabutments on each of said right and left tool slides which engage saidjaws to squeeze said wire and form a smoothly curved wire base.

8. A wire forming machine for forming double torsion springs comprising,a base, a coiling station having a center forming arbor movable betweenat least a bottom position and a raised position and a stationaryelement positioned to the rear thereof, a front slide with a bow-formingtool having a pair of jaws movable onto said forming arbor in saidbottom position to form a bow at the center of a piece of wire to formthe wire into a U-shape with a wire base and a pair of legs extendinghorizontally therefrom, said legs lying against the sides of thestationary element and under horizontal surfaces formed thereon, rightand left tool slides movably mounted on said base and a rotatablecoiling head with catch pin on each thereof, means including cams formoving said right and left slides toward each other to bring saidcoiling heads to the wire legs and said catch pins over the top of thewire legs, and means for rotating said coiling heads a desired number ofrevolutions to form the desired number of coils in each leg with saidforming arbor in its raised position which permits advance of the wirebase toward the coiling heads to provide wire for the coils and withsaid horizontal surfaces on the stationary element preventing rotationof the wire base.

9. A machine as defined in claim 8 including abutments on each of saidright and left tool slides which en age said pair of aws to squeeze saidwire and form a smoot ly curved wire base.

10. A machine as defined in claim 8 wherein each of said coiling headsis rotatably mounted in its respective slide, a pinion affixed to eachhead, a pair of racks associated one with each pinion, means foractuating said racks from the rear slide cam of the machine including abridge moved by the cam, and means for slidably connecting the end ofeach rack to the bridge whereby the bridge movement imparts linearmovement to the racks while permitting movement of the racks lengthwiseof the bridge as the right and left tool slides move toward and awayfrom each other.

11. A machine as defined in claim 8 wherein said forming arbor has asurface in the plane of said wire base in said raised position to definea limit of advance for the wire base in the coiling operation.

12. A machine as defined in claim 8 wherein means are provided to causeprogressive separating movement of said coiling heads as the coils areformed in said legs.

13. A machine as defined in claim 12 wherein said stationary element hasa pilot hole, a coiling arbor extending from one coiling head and of alength to extend through the pilot hole and into a central recess in theopposite coiling head and remain in said recess during said progressiveseparating movement.

14. A method of forming a double torsion spring at a single stationwherein a length of wire is bent into a U-shape with a pair of legsextending from a central wire base, the legs are gripped and rotated andwith the central wire base advancing toward the locations where the wirelegs are gripped to provide wire length for the coils whereby the freeends of the completed spring are substantially equal in length to thefree length of said wire legs beyond the location of gripping thereof,and with the distance between the gripping locations on the two legsincreasing during rotation of the legs to form outwardly extendingcoils.

1. The method of forming a double torsion spring comprising thefollowing steps, feeding a continuous length of wire to a formingstation, cutting a section of wire from said wire length at said formingstation, forming the wire section at said forming station into anapproximate U-shape with a pair of spaced legs, and coiling a pluralityof coils in each of said legs simultaneously at said forming station byholding and rotating each of said legs and with the base of the wiresection being held against rotation but movable toward the coils toprovide sufficient wire for the coils, the spacing between the locationswhere the two legs are held increasing as the legs are rotated to formoutwardly extending coils.
 2. The method as defined in claim 1 whereinsaid legs are engaged by rotatable members which slightly bite into thewire.
 3. The method as defined in claim 1 wherein said wire base is heldagainst rotation by engaging the top of the wire legs between the wirebase and the coiling location to permit sliding movement of the legs asthe coils are formed.
 4. A machine for forming double torsion springscomprising, a base, wire feeding and straightening means thereon, acoiling station having a center form with a forming arbor and astationary element, a front slide with a bow-forming tool movable ontothe forming arbor to form a center bow in a length of wire to bend thewire into a general U-shape with a base and a pair of legs against thestationary element, left and right tool slides each carrying a rotatablecoiling head and a catch pin movable toward each other to engage thespaced-apart wire legs, means for simultaneously rotating said coilingheads and catch pins to form a plurality of coils in each wire leg withprogressive separating movement of the coiling heads, means retractingsaid formIng arbor to permit movement of said wire base toward thecoiling heads to provide wire for the coils, and means engaging saidwire to hold said wire base against rotation while permitting advancethereof.
 5. A machine as defined in claim 4 wherein said forming arborhas a surface in the plane of said wire base after said retraction todefine a limit of advance for the wire base in the coiling operation. 6.A machine as defined in claim 4 wherein said stationary element has apilot hole, a coiling arbor extending from one coiling head and of alength to extend through the pilot hole and into a central recess in theopposite coiling head and remain in said recess during said progressiveseparating movement.
 7. A machine as defined in claim 4 wherein saidbow-forming tool has a pair of spaced-apart jaws spring-urged towardeach other which move along opposite sides of said forming arbor to formthe center bow, and abutments on each of said right and left tool slideswhich engage said jaws to squeeze said wire and form a smoothly curvedwire base.
 8. A wire forming machine for forming double torsion springscomprising, a base, a coiling station having a center forming arbormovable between at least a bottom position and a raised position and astationary element positioned to the rear thereof, a front slide with abow-forming tool having a pair of jaws movable onto said forming arborin said bottom position to form a bow at the center of a piece of wireto form the wire into a U-shape with a wire base and a pair of legsextending horizontally therefrom, said legs lying against the sides ofthe stationary element and under horizontal surfaces formed thereon,right and left tool slides movably mounted on said base and a rotatablecoiling head with catch pin on each thereof, means including cams formoving said right and left slides toward each other to bring saidcoiling heads to the wire legs and said catch pins over the top of thewire legs, and means for rotating said coiling heads a desired number ofrevolutions to form the desired number of coils in each leg with saidforming arbor in its raised position which permits advance of the wirebase toward the coiling heads to provide wire for the coils and withsaid horizontal surfaces on the stationary element preventing rotationof the wire base.
 9. A machine as defined in claim 8 including abutmentson each of said right and left tool slides which engage said pair ofjaws to squeeze said wire and form a smoothly curved wire base.
 10. Amachine as defined in claim 8 wherein each of said coiling heads isrotatably mounted in its respective slide, a pinion affixed to eachhead, a pair of racks associated one with each pinion, means foractuating said racks from the rear slide cam of the machine including abridge moved by the cam, and means for slidably connecting the end ofeach rack to the bridge whereby the bridge movement imparts linearmovement to the racks while permitting movement of the racks lengthwiseof the bridge as the right and left tool slides move toward and awayfrom each other.
 11. A machine as defined in claim 8 wherein saidforming arbor has a surface in the plane of said wire base in saidraised position to define a limit of advance for the wire base in thecoiling operation.
 12. A machine as defined in claim 8 wherein means areprovided to cause progressive separating movement of said coiling headsas the coils are formed in said legs.
 13. A machine as defined in claim12 wherein said stationary element has a pilot hole, a coiling arborextending from one coiling head and of a length to extend through thepilot hole and into a central recess in the opposite coiling head andremain in said recess during said progressive separating movement.
 14. Amethod of forming a double torsion spring at a single station wherein alength of wire is bent into a U-shape with a pair of legs extending froma central wire base, the legs are gripped and rotated and with thecentral wire baSe advancing toward the locations where the wire legs aregripped to provide wire length for the coils whereby the free ends ofthe completed spring are substantially equal in length to the freelength of said wire legs beyond the location of gripping thereof, andwith the distance between the gripping locations on the two legsincreasing during rotation of the legs to form outwardly extendingcoils.